The purpose of this proposal is to produce a Fifth Edition of our book of protein and nucleic acid sequences of immunoglobulins, T- cell receptors and other members of the immunoglobulin superfamily entitled "Sequences of Proteins of Immunological Interest" the Fourth Edition of which will appear early in 1987. We intend, as for previous editions, collect and organize all sequences in the format used in earlier editions, which provides classified and aligned sequences of amino acids and codon such that rapid examination and comparisons of data are possible. Relevant data on sources, antibody specificities and other biological properties are provided, together with statistical calculations, variability plots, summary tables of occurrences of amino acid and codon usages at various positions in variable regions of light and heavy chains of immunoglobulins, T-cell receptor for antigen, other members of the immunoglobulin superfamily and related proteins of immunoglobulin interest. An introduction outlining how to use the information and a survey of the state of the field is included. As has been done for the data in the four previous editions, the research implications of the data will be analyzed continuously for insights into the ways in which antibody specificity, complementarity and diversity are generated in various species at the genetic level, the relation of sequence and antibody specificity, the nature of the contacting residues in various antibody combining sites in relation to x-ray crystallographic structures, the preparation of detailed maps of complementarity-determining residues to locate residues involved in idiotypic and antibody specificity, the study of the nature of the sequences and specificities of anti-idiotypes and anti-anti- idiotypes especially to attempt to understand how anti-anti- idiotypes may have a site which reacts with the original antigens. Searches will also be made in the various immunoglobulins for biologically active peptides such as tuftsin which is present in the CH2 domains of IgG1, IgG3 and IgG4 and to identify residues involved in other biological activities.